1. Field of the Invention
The present invention relates to wrappers for smoking products such as cigarettes. Cigarettes are conventionally made by wrapping tobacco in paper which is made from flax or other cellulosic fibers and calcium carbonate filler. Papers of this general description are standard in today's cigarettes and are available from a number of sources. The burning cigarette releases smoke which may be classified as sidestream when it emanates from the lit-end of the cigarette or mainstream when it is drawn through the tobacco column to the smoker. The present invention is directed to an improved wrapper and resulting smoking article that materially reduce the quantity of sidestream smoke.
2, Description of the Art
Various attempts have been made to reduce the level of sidestream smoke. However, none has been successful to the point of significant commercial exploitation. For example, U.S. Pat. No. 4,225,636 to Cline, et al. issued 30 Sept. 1980 is directed to the use of high porosity carbon-coated cigarette papers disclosed to provide substantial reductions in both mainstream and sidestream smoke. U.S. Pat. No. 3,744,496 to McCarty, et al. issued 10 July 1973 is also directed to a carbon-filled wrapper which is preferably treated with compounds such as alkali metal hydroxides, bicarbonates and carbonates. It also has been recognized that some smoking articles wrapped in tobacco leaf release lower amounts of sidestream smoke, but such wrappers are not practical for use on cigarettes. These products, as well as those resulting from other attempts at sidestream reduction, have suffered either from excessive cost or adverse effects relating to mainstream particulate deliveries, draw, taste, or other factors such as burn rate. U.S. Pat. No. 4,461,311 to Mathews, Mattina and DeLucia dated 24 July 1984 describes a further improvement in wrappers incorporating extraordinary amounts of alkali metal salts. While successfully reducing sidestream smoke, cigarettes with such wrappers have exhibited taste modifications noticeable to some smokers. U.S. Pat. No. 4,805,644 issued 21 Feb. 1989 to Hampl, Fields and Bullwinkel, describes sidestream-reducing cigarette papers having defined surface area characteristics, but which may be further improved in physical properties such as strength. While these improvements have been demonstrated, even better means for reducing sidestream smoke are desired.
As those skilled in this art will appreciate, it is conventional to incorporate any of a wide variety of filler compounds in papers for cigarette wrappers. The above-described U.S. Pat. No. 3,744,496 to McCarty, et al. issued 10 July 1973, for example, discloses the use of carbon as a filler. U.S. Pat. No. 4,461,311 to Mathews, Mattina and DeLucia dated 24 July 1984 teaches the use of calcium carbonate, and a series of patents to Cline or Cline, et al., including U.S. Pat. No. 4,231,377 dated 4 Nov. 1980, teaches the use of various magnesium compound fillers. It has also been suggested that conventional clays may be one of a number of materials suitable as fillers for cigarette wrapper papers. Examples of such teachings include U.S. Pat. No. 2,181,614 to Striefling dated 28 Nov. 1939. Moreover, conventional clays have been taught as suitable for fillers for smokeable compositions, per se. Finally, fillers such as attapulgite clay are known for use in tobacco smoking preparations as taught in U.S. Pat. No. 3,049,449 to Allegrini dated 14 Aug. 1962, for example.
In spite of the foregoing information available to those skilled in this art, it remains desired to obtain reductions in sidestream smoke more efficiently and at the same time improve physical properties of the paper without adverse effects on other smoking properties such as taste or ash color.